The present invention relates in general to mufflers for the exhaust system of vehicles with internal combustion engines, and, more specifically, to manufacturing a muffler shell from a sheet metal blank.
In the mass production of mufflers for the exhaust systems of motor vehicles and the like, a construction based on an outer, tubular shell made from sheet metal is commonly used due to advantages of low material cost and the availability of automated manufacturing processes and equipment. After forming the tubular shell, the addition of internal baffles, pipes, and end caps completes the muffler.
When installed into a vehicle such as a car or truck, a bottom side of the muffler is typically exposed to an open space beneath the vehicle. During vehicle movement, a high velocity air flow beneath the vehicle can interact with the muffler and any gaps, connecting structures, or protective liners/shields spaced from or surrounding the muffler. The interaction can create undesirable turbulence that affects vehicle performance and increases noise in the passenger cabin. The interaction can be especially pronounced when the muffler is mounted transversely to the direction of vehicle travel.
Applicant's co-pending U.S. application Ser. No. 14/549,188, filed Nov. 20, 2014, entitled “Muffler Shield and Muffler Assembly Employing the Same” (which is incorporated herein by reference in its entirety), discloses the addition of an aerodynamic shield to occupy a gap adjacent the muffler. In particular, a separate aerodynamic form is fabricated and then is attached to the outside surface of the muffler body. However, the separate fabrication and attachment of an aerodynamic shield structure to fill a gap around the muffler results in increased cost and manufacturing complexity.